1. Field of the Invention
The present invention relates to an apparatus and method for managing pressure in a wellbore. More specifically, the invention relates to the use of swirling fluids to maintain a wellbore at a desired pressure.
2. Description of the Related Art
In hydrocarbon producing wells, the wellbore may be completed by placing a casing inside the wellbore which is perforated along a producing or formation zone. Formation fluids generally contain a layer of gas above a layer of oil, which in turn is above a layer of water. The boundary between these 3 layers may not be consistent, making it difficult to produce only the desired fluid throughout the entire production length of the casing. Also, the formation itself may have irregular properties, or defaults that cause production to vary along the length of the casing. However, even flow along the perforated casing is usually desired.
Producing along the length of the wellbore at uneven rates may cause another of the formation zones to be produced. For example, in a oil producing well, water may begin to make its way into the casing in one localized area, significantly reducing oil production as well as the quality of the produced fluids. In order to maintain consistent production rates along the length of the perforated casing, one or more inflow control devices may be placed in the wellbore to assist in controlling the flow of fluids into the wellbore. Multiple fluid flow devices may be installed, each controlling fluid flows along a section of the wellbore. These fluid control devices may be separated from each other by conventional packers. Other benefits of using fluid control devices include increasing recoverable reserves, minimizing risks of bypassing reserves, and increasing completion longevity.
Prior art fluid control devices include both active flow control devices and passive flow control devices. Active flow control devices tend to be relatively expensive and include moving parts, which require maintenance and repairs, increasing costs and reducing reliability. Passive inflow control devices (“ICDs”) that are able to control fluid flow into the wellbore are therefore desirable. Passive ICDs are reactive only and may restrict flow by creating a pressure drop or flow rate reduction in order to provide a more even production profile. In either case, current ICDs are susceptible to plugging or clogging, with little or no options for remediating the problem.
Therefore a passive ICD able to address the above concerns is desirable.